This application relates to mobile energy storage systems in commercial buildings.
Electric vehicles (EVs) have attracted much attention in recent years mainly due to economic and environmental concerns. It is expected that 3 million EVs to be on the read in California by 2015. While wide-scale penetration of EVs in electric systems brings new challenges to electric systems that need to be addressed, at the same time, it shows great potentials and new opportunities to improve efficiency of energy and transportation sectors. One can take advantage of the unique characteristics of these relatively new components of energy systems to address some of the existing issues of the grid.
EVs can be considered as Mobile Energy Storage (MES) that are available only during certain hours of a day. The presence of these MESs in an energy system, e.g., commercial building, offices, schools, colleges, etc., depends on many uncertain parameters such as end-users driving patterns, weather conditions, fuel price, and electricity price. Also, the initial level of energy stored in each MES connected to an energy system is an uncertain parameter. These probabilistic parameters might follow specific patterns that are associated with some probability distribution functions, and can be forecasted with a degree of uncertainty.
The use of EVs is particularly of importance for commercial buildings, where employees can plug in their EVs to the building energy system to be charged and/or discharged controlled by the Energy Management System (EMS) of the building. This invention investigates the optimal planning, operation, and control of such MESs using stochastic optimization techniques.
In the context of smart grids, smart distribution systems are envisioned as coupled microgrids (μG) that not only are connected to the grid, but also utilize Distributed Energy Resources (DERs) to generate power. High level of DERs integration in μGs raises concerns about the availability of high quality power supply mainly due to the variable and intermittent nature of power generation by Renewable Energy Resources (RESs). To cope with these issues, energy storage systems have been proposed to be used in μGs with DERs. When added, an energy storage system can immediately improve μGs' availability. Today, pumped hydro, flywheel, compressed air, and different types of batteries are the main energy storage technologies considered in the US electric power grid. In addition to these technologies, EVs can be considered as MES that are available only during certain hours of the day. FIG. 1 shows an exemplary load profile of a large commercial building office during weekdays and weekends for summer and winter. As shown therein, peak energy usage occurs during working hours, and drops off during non-working hours.